Daniel ate 4 slices of cake. William ate 1 slice. If Daniel ate $\dfrac{4}{9}$ of the cake, what fraction of the cake is remaining?
Explanation: If 4 slices represent $\dfrac{4}{9}$ of the cake, there must have been a total of 9 slices. $\text{fraction of cake remaining} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 5 slices, which leaves 4 out of 9 slices remaining. There is $\dfrac{4}{9}$ of the cake remaining.